310 



THE POPULAR EDUCATOR. 



They are composed of carbon, hydrogen, and oxygen; the 

 carbon always is present in the proportion of six atoms, whilst 

 the oxygen and hydrogen appear in the exact proportion to form 

 a whole number of molecules of water. Hence the sugars have 

 been called hydrates of carbon. Their various decompositions 

 are effected by the removal or addition of the elements of water ; 

 when oxidised, they generally yield oxalic acid. 



The chief sugars are cane sugar, or sucrose (C ia H. >s O n ) ; 

 grape or starch sugar, or glucose, 2(C 8 H 1S O 8 ,H 2 0) ; and milk 

 sugar, or lactose (C 12 H 22 11 ,H 2 O). Besides these there are 

 some leas prominent members of the group. 



Cane Sugar, or Sucrose (C,,H M O 11 ), is the sweetening principle 

 io. a great number of tropical fruits ; it is chiefly procured for 

 the market from the sugar-cane, the maple tree, and beetroot. 

 It is also found in small quantities in carrots and turnips, and 

 in the chestnut and pumpkin. 



It is soluble in water and alcohol, but ether is unable to 

 effect its solution. When its water solution is evaporated, 

 it becomes deposited in crystals oblique rhomboidal prisms 

 this is tke sugar-candy of the confectioner. Its brown 

 colour depends on the state to which the syrup has been 

 clarified before the crystallisation. Loaf sugar is composed 

 of innumerable small crystals, which are transparent ; its 

 dazzling whiteness is due to the reflection of the light from 

 their many faces. 



If & solution of sugar be kept at the boiling point for some 

 time, it gradually loses the viscid nature of a syrup, exhibits an 

 acid reaction, and refuses to crystallise. 



It is now called inverted sugar, and its peculiar properties 

 seem to be due to the fact that another molecule of water has 

 been assimilated, its formula being C 12 H 24 O| 2 . If the boiling 

 still be continued for some hours more, water is taken up, and 

 grape sugar is the result, 2(C 6 H 12 O 6 ,H 2 G). These effects are 

 produced with greater rapidity if any of the strong acids be 

 present in a small proportion ; and hence, to prevent this 

 change, lime is mixed with the juice of the sugar-cane as soon 

 as it is expressed. 



Sugar possesses eminent antiseptic powers, and therefore it 

 is much used in " preserving." If spread over any fermentable 

 or decaying matter, it will arrest the action. 



Manufacture of Sugar. The canes are cut close to the soil 

 before they flower. In the rolling mill they are crushed between 

 grooved steel rollers. The juice thus expressed is so readily 

 fermentable that it may not be left for half an hour, but is 

 immediately mixed with about ^ its weight of lime, and heated 

 to 60 Cent, in copper vessels. Here the albuminous constituents 

 of the juioe coagulate, and are skimmed off. This necessary 

 heating has the effect of inverting some of the sugar, and ren- 

 dering it of the uncrystallising quality ; and much more would 

 be ao treated were it not for the lime, which neutralises 

 the free acid. It is transferred from the clarifiers to shallow 

 wooden coolers, and finally to the pottiny-casks, which have per- 

 forated bottoms ; and in the course of four or five weeks all the 

 molasses the inverted sugar drains off, leaving "raw sugar." 

 A gallon of juice generally yields a pound of sugar. 



Refining. If loaf-sugar be required, this raw sugar is mixed 

 with one-third of its weight of lime-water, which contains three 

 or four per cent, of " bone-black." After being heated by in- 

 jections of steam, it is filtered through pipes made of cotton 

 twill. Sometimes the serum of bullock's blood is added to this 

 syrup, which, as it coagulates, gathers in its meshes the me- 

 chanical impurities. 



The brown syrup is now bleached by allowing it to filter 

 through some twelve feet of animal charcoal, which is made by 

 calcining bones in closed vessels. 



This clear liquid must be evaporated down to a thicker consis- 

 tency ere it will crystallise ; but owing to its viscidity a tem- 

 perature of 110 Cent, is required for its ebullition. Were the 

 syrup raised to this heat, much of it would become inverted, 

 and much would be burnt, and so colour the sugar. The diffi- 

 culty is removed by conducting the evaporation in a spherical 

 closed vessel the lower half of which is double by means of 

 a powerful air-pump ; a partial vacuum is produced, and when 

 steam is injected into the cavity at the bottom of the pan, 

 the syrup boils at about 70 Cent. When it has reached a 

 certain consistency it is placed in a vessel heated by steam to 

 1 70 ; here it is beaten about by wooden oars until it appears 

 granular, when it is placed in conical vessels of earthenware, 



which have a hole at their apex. This hole is stopped by a plug 

 for a few hours, and when it is removed the uncrystallisable 

 syrup drains out ; the loaf is finally dried, and finished in a 

 lathe for the market. 



Maple Sugar is a product of the American forests. The 

 tree is tapped on its sunny side ; two holes, about half an in^h 

 deep, penetrate the bark ; reeds are fitted into these, and the 

 rising sap or, if the operation be conducted in the autumn, the 

 descending sap flows through the reeds into vessels placed for 

 its reception. Each hole exudes as much as six gallons a day, 

 and if the tree be old this quantity yields a pound of sugar. 



Beetroot Sugar. The manufacture of sugar from the white 

 beet owes its rise to the wars of Napoleon. When the French 

 supply of sugar from the West Indies was cut off, they had 

 recourse to its extraction from beetroot. The expressed juice 

 contains about ton per cent, of saccharine matter. The clarifi- 

 cation, etc., is conducted upon the same principles as those 

 given above. 



Grape or Starch Sugar Glucose (C 6 H,.,O 6 ,H 2 O). This sugar 

 may be prepared by boiling starch in twice its weight of water, 

 acidulated with one per cent, of sulphuric acid. 



Starch is C| 2 H 20 O 10 , so that two molecules of glucose may 

 be supposed to be formed by inserting four molecules of water 

 into one molecule of starch. 



C la H ao O 10 + 4H a O = C l3 H a8 0, t , or 2(C 6 H 1!1 O.,H S O). 

 It has been shown that this change can also be effected by 

 diastase. 



This sugar has not the same power of sweetening as cane 

 sugar; 1 part of the latter is equal in this respect to 2 4 of the 

 former. Neither is it so soluble in water, but is more readily 

 taken up by alcohol. The action of sulphuric acid readily distin- 

 guishes these two varieties of sugar. Cane sugar is decom- 

 posed by the acid, but with grape sugar a compound is formed 

 sulpho-saccharic acid. 



Sugar of Milk, or Lactose (C 12 H 2 .,0,,,H.jO), is peculiar to the 

 milk of the mammalia. It is fitted to be an ingredient of this 

 secretion by its non-fermenting quality. It may be procured 

 by evaporating whey until it reaches the crystallising point. 

 Then the lactose appears as semi-transparent, right, four-sided 

 prisms, terminated by pyramids, on pieces of thread or wood, 

 which are placed in the liquid to form nuclei. It has even less 

 sweetening power than glucose, it is more difficult of solution in 

 water, and insoluble in alcohol. 



Frv.it Sugar, or Lcevulose (C 6 HjjO a ), which is found in ripe 

 fruits, seems to be a mixture of cane and inverted sugars. By a 

 spontaneous action the latter variety separates into crystallised 

 starch sugar and an uncrystallisable syrup. This may be 

 noticed in the case of preserved fruits. They are covered with 

 a candy which does not possess a sweetness equal to that of 

 cane sugar. 



FERMENTATION. 



A ferment is an active principle of organicised matter, which 

 is capable of setting up decomposition in organic matter. It is 

 now generally admitted that ferments are vital organisms 

 fungi, infusoriae, etc., the very lowest forms of vegetable and 

 animal life. These seedlings of life are everywhere. The very 

 dust which a sunbeam reveals floating in the air contains them. 

 If their vitality be destroyed in any body, that body will not 

 ferment : for instance, if milk be made to boil under a pressure 

 of 1^ atmosphere, the high temperature kills these organisms ; 

 and if the liquid be now kept from the air, or such air only be 

 allowed to come into contact with it as has been strained by 

 passing through a plug of cotton wool, it may be kept for any 

 length of time without undergoing any decomposition. 



Fermentation has been classed by Miller in three divisions 



1. Where the body is simply broken up into compounds of lesi. 

 complicated structure, thus : 



C.H^O, (fruit sugar) gives 2CO, (carbonic acid) + 2C 3 H,O (alcohol). 



2. Where beyond this decomposition the elements of water 

 are separated, thus : 



C 8 H 14 O T (grape sugar) = 2CO a + 2C 3 H O + H,O. 



3. Where the elements of water are assimilated, and the new 

 body thus formed split up into simpler compounds. Thus : 



Cane Suffar. Fruit Sugar. 



(1) C^H^O^ + H,O = 2C H 12 O.. 



(2) C.H.,0,, = 2CO-, + '^C,,H.O. 



